The present invention relates to a method and system of preventing the addition of the wrong type of fuel to a fuel tank, by monitoring the vapor pressure of the fuel being added, and if detected as the incorrect fuel, shutting off the supply by activating the fuel pump's shutoff via maintaining a vacuum on the fuel nozzle or by inducing increased back pressure in the fuel tank.
Because of differing types of fuel being offered at filling stations, it is frequent that the wrong type of fuel will be added to a vehicle's tank. Particularly troublesome is the confusion between diesel and gasoline fuels, which because of their chemical properties, are not interchangeable. Furthermore, the addition of the wrong type of fuel will not only fail to power the vehicle, but also exposes the engine to the possibility of serious damage.
Various methods have been implemented to prevent the confusion of the fuels, including the manufacture of diesel fuel nozzles and filler necks being a larger diameter than their gasoline counterparts. This works relatively well for automotive use, since the fuel aperture in gasoline-powered cars are intentionally narrower as to prevent the introduction of a diesel nozzle into the filler neck. However, the converse is not true. Diesel filler necks readily accept the smaller gasoline filler nozzle, and so without proper attention, large amounts of money can be lost on an oversight when the wrong fuel is added to an engine and causes is to malfunction, or in some cases, to injure those who may be in the proximity.
The present invention alleviates this problem by effectively preventing the addition of any type of fuel that can be identified by vapor pressure from being added to a properly equipped fuel tank. Additionally, having such a device capable of being retrofitted to current vehicles enables end users to equip their own vehicles, rather than relying upon filling stations to retrofit their pumps with a similar system.